Generally, a post-processing system for an internal combustion engine is equipped to remove carbon monoxide, hydrocarbons, particulate matter, and nitrogen oxide that are generated from an engine.
The post-processing system may include a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), a reducing agent injection apparatus and a selective catalytic reduction (SCR).
The diesel oxidation catalyst serves to oxidize carbon monoxide or hydrocarbons included in the exhaust gas, and burn some of the particulate matter using the oxidation heat to reduce the amount of particulate matter.
The diesel particulate filter serves to filter the particulate matter included in the exhaust gas and burn the collected particulate matter at a predetermined temperature to remove the particulate matter.
The reducing agent injection apparatus servers to inject a reducing agent into the exhaust gas and the selective catalytic reduction uses the reducing agent included in the exhaust gas to oxidize/reduce the nitrogen oxide to remove the nitrogen oxide as nitrogen and water.
Methods have been researched for using noble metal components for applications including the diesel oxidation catalyst or the diesel particulate catalyst. These applications include oxidizing and removing the carbon monoxide or the hydrocarbon, and oxidizing the nitrogen monoxide to generate nitrogen dioxide to a later stage thereof. These applications may improve occlusion performance of the selective catalytic reduction for the nitrogen oxide and improve the efficiency thereof.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.